Wheat is a general term for triticum, which is the most widely distributed food crop with the largest consumption population in the world, known as “worldwide food”. Gluten powder, also known as vital wheat gluten, refers to the remaining unmodified gluten powder after washing away starch and other water-soluble substances with wheat flour as raw material, and it is a nutritious plant protein source. In the protein composition of the wheat, gluten powder contains about 70% to 80% of protein as the main component, and also contains a small amount of starches, fibers, sugars, fats, lipids, minerals, etc. Wherein, gliadin accounts for 40% to 50%, glutenin for 30% to 40%, globulin for 6% to 10%, and albumin for 3% to 5%, of the total protein.
In the amino acid composition of the wheat, based on total amount of amino acids of wheat protein, there are about 35% of total glutamic acid Glx (Gln+Glu), about 16% of proline, and smaller amount of basic amino acid. Glutamine is the most abundant free amino acids in animal plasma and tissues, which accounts for about 40% to 60% of the total free amino acids. Glutamine is a very important essential amino acid and intestinal essential amino acid with specific nutritional effect. Since Gln has the characteristics of low solubility in water, being unstable in aqueous solution, and acid-sensitive, etc., nutritional and physiological functions of Gln in enteral, parenteral or oral nutrition cannot be fully realized. The peptide obtained by the hydrolysis of protein has better nutrition than the protein, and experiments have confirmed that the peptide has higher absorptivity than amino acid, and is easier and faster to be absorbed and utilized by human body through small intestine membrane.
With the rapid development of science and technology, people have had more deep knowledge to composition and functional properties of protein of gluten powder, which has greatly broadened its application fields. In recent years, due to the constant increase in the production of gluten powder, the traditional market is becoming saturated. So it is very urgent and necessary to develop an industrial method for deep and fine processing of the gluten powder to explore high value-added foodstuffs for maximizing gluten powder nutrition.
Enzymolysis of wheat gluten powder by protease may enzymolyze the whole protein into oligopeptides with smaller molecular weight and greatly increase the solubility of the product and release the glutamine therein, which facilitates preparation of glutamine-rich wheat glutamine peptide. The successful preparation of wheat glutamine peptide provides a new industrial way for deep processing wheat gluten powder agricultural products as traditional food, so that the abundant ordinary food protein resources-wheat gluten powder are fully utilized, which greatly expands the application fields of the wheat gluten powder as a raw material for the traditional ordinary food, and improves the added value of bulk agricultural products, thus realizing greater economic value and improving the overall social benefits.
Compared with the original protein, wheat glutamine peptide with small molecule has good processability. For example, wheat glutamine peptide is more stable under acidic conditions, not easy to precipitate; and it will not heat coagulated when heated and has no protein denaturation problems. The wheat glutamine peptide has good water-solubility due to its small molecular weight and large polarity. Wheat glutamine peptide, as a food raw material, is characterized by high concentration, low viscosity, rapid soluble in water, no residue, etc., and will maintain good flowability even at high concentration of 50%. Wheat glutamine peptide has strong hygroscopicity and moisture retention, which can inhibit the protein from forming a gel and, thus, adjust the hardness of protein food.
Due to a series of excellent food processabilities, wheat glutamine peptide can be mixed with proteins from various sources, to improve their nutritional value, and also can be used to produce instant drinks, functional drinks, meat products, milk products, baked goods and other diverse food. In addition, wheat glutamine peptide can be used as a protein supplement in diet for the elderly, sports nutrition, weight controlling, etc., or as a nutritional component of foods provided for patients with digestion and absorption dysfunctions and also as baby food, and also can be added into the emerging wine beverage products.
Wheat glutamine peptide, due to its high safety, nutritional value and good processability, can be added into many food products, and thus has a good market prospect.